Degradable Poly(β-amino esters): Synthesis, Characterization, and Self-Assembly with Plasmid DNA

Abstract

Poly(β-aminoesters) 1−3 were synthesized via the addition of N,N‘-dimethylethylenediamine, piperazine, and 4,4‘-trimethylenedipiperidine to 1,4-butanediol diacrylate. Polymerization proceeded exclusively via the conjugate addition of the secondary amines to the bis(acrylate ester). Polymers were isolated in up to 86% yields with molecular weights ranging up to 31 200 relative to polystyrene standards. The polymers degraded hydrolytically in acidic and alkaline media to yield 1,4-butanediol and β-amino acids 4a−6a and the degradation kinetics were investigated at pH 5.1 and 7.4. In general, the polymers degraded more rapidly at pH 7.4 than at pH 5.1. In initial screening assays, both the polymers and their degradation products were determined to be noncytotoxic relative to poly(ethylene imine), a polymer conventionally employed as a synthetic transfection vector. Polymers 1−3 interacted electrostatically with polyanionic plasmid DNA in water and buffer at physiological pH, as determined by agarose gel elec...